Dynamo-electric machine



AFT-i115, 1930 J. M. PESTARINI DYNAMO ELECTRJC MACHINE Filed Aug. 18,1927 10a 301 204 50g 20a Um w @y t .e

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Joann; I. Pvnsrannu,

Patented Apr. 15, 1930 OUEN, FRANCE, ASSIGNOB '.lOV GENERAL 4ELEGIZB'ICOOI- PANY, CORPORATION OF NEW YORK' 4 brume-morale mennen applicationmea august is, 1921, semina. massa'ana in nam December 1s, 192e.

invention relates to dynamo-electric M r macliines and particularly toarmature windingsv for such machines.

Armature windings have been made here-1 tofore comprising a plurality ofelectrically parallel coils arrangled in. adjacent slots and connectedbetween t e same commutator segments for the purpose of reducing thevinductive reactance of the winding elements short circuited durincommutation, as shown for example in the S. Patent N o. 1,502,931 toWhitaker of July 29, 1924. These windings have been made of electricallyparallel long and short pitch coils, which was necessary in order toinsure the slot conductors of each coil bein infeldsvof equal fluxdensity and the avoi ance of circulating currents in the coils when theywere short circuited during commutation. A disadvantage of such aconstruction is that the coils of different pitch connected in parallelprovidecurrent paths of unequal length and resistance which results inunequal current distribution between them. v

The object of my invention is to provide an armature construction inwhich unequal current distribution will be avoided and that portion ofthe winding short circuited during commutation will be of low reactance.Equal current distribution is obtained in accordance with my invention,by connecting two independent armature windings of equal length andresistance to separate commutator seg- 3 ments, and employing brushes toconnect the windings in parallel at the commutator. These windings eachcomprise coils of difierent pitch arranged in such relation that thecoils short circuited during commutation eX- tend throughseparate slotsso that the coils are of as low inductive reactance as priorconstructions having unsymmetrical winding elements`v connected inparallel within the armature winding, without the usual disadvantage ofunequalrcurrent distribution.

My invention will be more fully set forth in the following descriptionreferring to the accompanying drawing, and the features of novelty whichcharacterize my invention will be pointed out with particularity in theclaims annexed to and specification. Y y

,In thedrawing Fig. 1 is a diagram of an armature embodying myinvention, and Fig. 2 is a modification thereof.

Referrin to the drawing, the armature shown vin ig. 1 includes twoindpendent windings 20 and 30 which are connected to separate commutatorsegments 20n and 30'L forming a part of this respectively, and whichextend throu h the armature slots numbered consecutivey for conveniencein explaining the construction. Each of these windings lnclude longpitch coils of slightly greater pitch than the ole pitch p, indicated inthe drawing, and s ort pitch coils of slightly less pitch than the polepitch p.

The winding 20 is a lap winding comprising a series of alternatelyarranged long pitch coils 21 and short pitch coils 22 extending throughodd numbered armature slots. In each of these slots is arranged a sideof a long pitch coil 21 and an ad]acent side of a short pitch coil 22both of which form a. art of the series of coils constituting the wining 20. The long pitch coil 21 extends from this slot through an oddnumbered slot at a distance therefrom slightly greater than the polepitch p. The short pitch coil 22-in the same I slot extends through anodd numbered slot at a distance there rom slightly less than the polepitch. It will be noted that the sides of these coils which are indifferent slots are displaced an equal amount on opposite sides of aslot displaced from the slot in which their sides aread] acent an amountequal to the pole pitch. For example, inv Fig. 1 a long pitch coil 21`and a short pitch coil 22 are arranged with their sides in slot 3, theother sides of these coils extending through slots 9 and 11 which areequidistant on each side respec-v tively of an even numbered slotlOdisplaced from the slot 3 a distance equal to the pole pitch p. The endconnections of the coils 21 and 22 adjacent in the series .of alternatecoils are connected to the same commutator segment20. The sides of coils21 and `22 which are in the same slot, are connected towcontig-y uoussegments 20; and the other sides of these coils, which arevin differentslots, are

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connected to segments 20'L separated by pairs of segments 30".

The winding 30, which is similar to the winding 20, is also a lapwinding comprising a series of alternately arranged long pitch coils 31and short pitch coils 32 extending through even numbered armature slots.The side of a short pitch coil 32 and the side of a long pitch coil 31are arranged adjacent in these slots, the other side of these coilsvbeingarranged in slots on each side of an odd numbered slot displaced adistance equal to the pole itch from that in which the coil sides are ajacent. For example, in Fig. 1 a long pitch coil 31 and a short pitchcoil 32 are arranged -with their sides in slot 2, the other sides ofthese coils extending through slots 8 and 10 which are equidistant oneach side respectively of an odd numbered slot 9 displaced from theslot'2 a distance equal to the pole pitch p. The end connections of thecoils 31 and 32 adjacent in the series of alternately arranged coils areconnected to the same commutator segment 30. The sides of Vcoils 31 and32 which are in the same slot are connected to contiguous segments 30;and the other sides of these coils, which are in different slots areconnected to segments 30a separated by pairs of segments 20a. In orderto avoid the necessity of crossing over the end connections leading tothe commutator the segments 20 and 30'al are arranged in alternatepairs.

The independent windings 2() and 30 are connected in parallel by thecommutator brushes, which are preferably equal in vwidth to fourcommutator segments, and as the windings 20 and 30 are symmetrical,equal current distribution between them is obtained. Any suitable brushwide enough to connect the windings 20 and 30 in parallel, shortcircuits portions of each of them simultaneously in parallelduringcommutation, and as the portions of the windings which are shortcircuited in parallel at the brushes extend-through separate slots theyare of comparatively low inductive reactance. v

The armature shown in Fig. 1 has four armature conductors per slot, butit is contemplated that my invention be used in armatures having anysuitable number of conductors per slot; for,example, Fig. 2 is a diagramof an armature having eight conductors per slot. In this constructiontwo independent symmetrical lap windings 40 and 50 are arranged in thearmature slots with the coil sides of each adjacent the coil sides olfthe other in the top and in the bottom of the s ots.

The winding 40 comprises a series of alternately arranged long pitchcoils 41 and short pitch coils 42 which are connected to pairs ofcontiguous commutator segments 40l separated by pairs of commutatorsegments 50 connected to the winding 50. The sides on one side of longand short pitch coils adjacent in the series, forming the winding 40,are arranged in the same slot on each side of a slot conductor of thewinding 50, and the other sides of these coils are arranged innon-adjacent slots displaced from the first mentioned an amountrespectively greater and less than the pole pitch. For example, in Fig.2 the sides of long and short pitch coils 41 and 42 are vin slot 2 andseparated by the side of a coil 52 of the winding 50. The long pitchcoil 41 extends from the slot 2 to the slot 1.1, and the short pitchcoil 42 extends from the slot 2 to the slot 9. It will be noted that theslots 9 and 11 are e uidistant from the slot 10 which is displaced fromthe slot 2 a distance equal to the pole pitch. The ends of the coilsadjacent the commutator including those conductors in the same slot areconnected to contiguous commutator segments 40, and the ends of thecoils includin inductors in separate slots are connecte to segments 40*separated by a pair of contiguous segments 50.

The winding 50 is similar to the winding 40 and also includes long pitchcoils 51 and short pitch coils 52 arranged alternately in series, thesides of which extend between those of winding 40. The long and shortpitch coils 51 and 52 are arranged in the same relation to the sides ofwinding 40 as the coils 41 and 42 are arranged relative to the inductorsof winding 50, and are connected to pairs of commutator segments 50which are separated by pairs of segments 40 connected to the winding 40.

The windings 40 and 50 are connected in parallel by the brushes whichare preferably equal in width to four commutator segments. Thesewindings provide current paths of equal resistance so that there istribution of current between them. Furthermore, portions of each of thewindings 40 and 50 are short circuited in parallel at the same timeduring commutation and as they are in different slots low inductivereactance of the coils being commutated is obtained.

Although I have set forth a specific embodiment of my invention asapplied to a multiplex lap winding it is apparent that my invention -isapplicable to a multiplex wave winding, and that modifications thereofmay be made by those skilled-in the art. I desire it to be understoodtherefore, that my invention is not limited to the particulararrangement shown and described, and I intend in the appended claims tocover all modications which do not depart from the spirit and scope ofmy invention.

' What I claimas new and ydesire to secure by Letters Patent of theUnited States, is 1. A dynamo-electric machine comprising an armaturehaving straight slots extending entirelyacross the face thereof, acommutator, and two independent windings connectan equal dised toseparate commutator segments, each .of

said windings comprising long pitch coils and short pitch coils arran edin said straight slots, each of said coi s being con- 5 nected to saidcommutator.

2. A dynamo-electric machine comprising an armature having straightslots extending entirely across the face thereof, a commutator, and twoindependent windings connectlo ed to separate commutator segments, eachof said windings comprising long pitch coils and short pitch coilsarranged alternately in series in said straight slots, each of saidcoils being connected to said commutator.

'15 3. A dynamo-electric machine comprising an armature having straightslots extending entirely across the face thereof, said armature having acommutator and two independent windings comprising long pitch coils andshort pitch coils, the conductors on one side of said long pitch coilsand short pitch coils being arran ed in the same armature slots each ofsai coils being connected to said commutator, and the conductors on theother side of the same coils being arranged in different slots.

4. A dynamo-electric machine comprising an armature, said armaturehaving a commutator and two independent windings comprising long andshort pitch coils, the conductors on one side of said long and shortpitch coils being arranged in the same armature slots, each of saidcoils being con nected to said commutator, and the conduc- 35 tors onthe other side of the sainev coilsV being arranged in different slots,one of said windings being connected to pairs 0f contiguous commutatorsegments separated by pairs of contiguous segments connected to 40 theother winding.

5. A dynamo-electric machine comprising an armature, said armaturehaving a commutator and two independent windings cornprising long andshort pitch coils arranged alternately in series, the conductors of o neside of said long and short-pitch coils bein arranged in the samearmature slots, each o said coils being connected to said commutaae ntor, and the conductors on the other side of the same coils being arraned indifferent J slots, one of said windings eing connected to pairs ofcontiguous commutator segments separated by pairs of contiguous segmentsconnected to the other winding; p In witness whereof, I have hereuntoset my hand this 27th da of July, 1927.

JOS PH M. PESTARINI.

